This invention relates to a process for producing sulfur from sulfur dioxide. More particularly, this invention relates to a process for producing sulfur by reaction of sulfur dioxide with agglomerating coal.
There is a great many processes known for removing sulfur dioxide from gases. It is important that sulfur dioxide be removed from gases exiting industrial plants since sulfur dioxide is an environmental pollutant. It is equally important to remove the sulfur dioxide from these gases due to the fact that the emission of sulfur dioxide to the atmosphere results in a loss of sulfur values since sulfur dioxide can be converted to sulfur. Many of the processes practiced commercially involve the use of reducing agents suth as natural gas or other gaseous reductants. It is also known that the sulfur dioxide in gases can be reduced by reaction with coal. The use of coal to reduce sulfur dioxide is attractive due to the expense and possible shortage of gaseous reductants. Coal is one of the most abundant fossil fuels and, in relation to other reductants for sulfur dioxide, is relatively inexpensive.
A process for the reduction of sulfur dioxide to sulfur employing coal is described in British Pat. No. 1,390,694. In the process described sulfur dioxide containing gases are introduced into a moving bed of particulate coal and reduced to elemental sulfur and/or hydrogen sulfide. For industrial application of this type of technology it is important that the coal used in such a process originates from deposits located short distances from the plant at which such a process is practiced. Coal occurs in many forms, some of which are "caking," or "agglomerating" coals and others which are non-caking or non-agglomerating coals. In employing the process of the British patent, it would obviously be important that the coal be non-agglomerating or non-caking since the moving bed of coal particles could be seriously affected by the type of coal employed. For example, if agglomerating coals were employed at the temperatures required in the process described, the coal particles would tend to stick to each other forming large lumps and rendering the process inoperative causing equipment breakdown. However, if, for example, the power plant, employing coal to reduce the sulfur dioxide content of the off-gases is located nearby a coal deposit which produced agglomerating coals, it would be very desirable to develop a process in which agglomerating coals could be employed for the reduction of the sulfur dioxide contents of the gases.
It is an object of this invention to provide a method for the efficient reduction of sulfur dioxide to sulfur using agglomerating coals as a reductant. This and other objects will become apparent from the description which follows.